pH decides whether fertiliser ever reaches the plant. On Central Highlands basalt fed inorganically for years, pH commonly drops to 4.5–5.0. In that band phosphorus is fixed by iron and aluminium, micronutrients lose availability, and useful microbial life all but stops. Adding more fertiliser to such a bed only raises the cost.
Structure is the parallel problem. Soil stripped of humus binds into clods, water runs off instead of soaking in, and fine roots cannot push through. The field sign is immediate: water standing on the surface after rain while the soil below 15 cm is still dry.
Neither is fixed by one application. Raising pH needs lime or dolomite at a rate calculated from the analysis, applied at least 15 days before organics so nitrogen is not lost. Reopening structure needs humus, which means organics at proper rates across several seasons — work counted in years, not rounds.
